This invention pertains generally to a display apparatus for a three-dimensional docking position control system and more particularly to a relative position representation image display apparatus for use with a remote manipulator. Remote manipulators are frequently employed in adverse environments to handle a variety of workpiece end effectors or tools. In the process of engaging one of these tools, the hand of the remote manipulator arm is moved up to the tool and accurately positioned so that a set of jaws or a clamp included with the hand can complete the attachment of the tool to the hand of the remote manipulator arm. Similarly, when a tool is released, it is often required that the arm withdraw along a precise path aligned with that tool to prevent bumping the tool or other adjacent objects. The required degree of three-dimensional precision accuracy with which this acquisition or docking operation is accomplished is related to the characteristics and relative stiffness of the manipulator arm and the tool acquired, and the amount of available clearance for the manipulator arm and the hand before the jaws are closed to engage the tool. To couple a manipulator arm successfully with a tool in a remote control system, it is necessary that the coupler first member on the manipulator arm and the tool holder second member be aligned very accurately. Before the operator shuts the coupler jaws, he must be sure that the coupler first member and the tool second member are at the correct spacing and in the same vertical and horizontal positions. If they are not, the jaws may damage the tool second member or even work loose and drop the tool if the grip is not secure.
During such an acquisition or coupling maneuver, the manipulator operator requires a high resolution feedback display of the jaw and the tool interface, especially when a high precision docking operation is required between a stiff manipulator arm and a rigid tool holder. Typical lighting conditions and the location of television cameras do not always allows adequate viewing of such an operation with the necessary depth perception capability for the relative positioning of the manipulator hand and associated workpiece tools in three-dimensional space. The coupling or docking operation can make use of a photoelectric docking sensor described in the above cross-referenced application Ser. No. 939,555, which sends out three voltage signals that indicate the difference in position along respective X, Y and Z axes between the coupler first member and the tool holder second member.